/***
 * ASM: a very small and fast Java bytecode manipulation framework Copyright (c) 2000-2011 INRIA,
 * France Telecom All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met: 1. Redistributions of source code must retain the
 * above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions
 * in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.googlecode.aviator.asm;

/**
 * A dynamically extensible vector of bytes. This class is roughly equivalent to a DataOutputStream
 * on top of a ByteArrayOutputStream, but is more efficient.
 *
 * @author Eric Bruneton
 */
public class ByteVector {

  /**
   * The content of this vector.
   */
  byte[] data;

  /**
   * Actual number of bytes in this vector.
   */
  int length;

  /**
   * Constructs a new {@link ByteVector ByteVector} with a default initial size.
   */
  public ByteVector() {
    data = new byte[64];
  }

  /**
   * Constructs a new {@link ByteVector ByteVector} with the given initial size.
   *
   * @param initialSize the initial size of the byte vector to be constructed.
   */
  public ByteVector(final int initialSize) {
    data = new byte[initialSize];
  }

  /**
   * Puts a byte into this byte vector. The byte vector is automatically enlarged if necessary.
   *
   * @param b a byte.
   * @return this byte vector.
   */
  public ByteVector putByte(final int b) {
    int length = this.length;
    if (length + 1 > data.length) {
      enlarge(1);
    }
    data[length++] = (byte) b;
    this.length = length;
    return this;
  }

  /**
   * Puts two bytes into this byte vector. The byte vector is automatically enlarged if necessary.
   *
   * @param b1 a byte.
   * @param b2 another byte.
   * @return this byte vector.
   */
  ByteVector put11(final int b1, final int b2) {
    int length = this.length;
    if (length + 2 > data.length) {
      enlarge(2);
    }
    byte[] data = this.data;
    data[length++] = (byte) b1;
    data[length++] = (byte) b2;
    this.length = length;
    return this;
  }

  /**
   * Puts a short into this byte vector. The byte vector is automatically enlarged if necessary.
   *
   * @param s a short.
   * @return this byte vector.
   */
  public ByteVector putShort(final int s) {
    int length = this.length;
    if (length + 2 > data.length) {
      enlarge(2);
    }
    byte[] data = this.data;
    data[length++] = (byte) (s >>> 8);
    data[length++] = (byte) s;
    this.length = length;
    return this;
  }

  /**
   * Puts a byte and a short into this byte vector. The byte vector is automatically enlarged if
   * necessary.
   *
   * @param b a byte.
   * @param s a short.
   * @return this byte vector.
   */
  ByteVector put12(final int b, final int s) {
    int length = this.length;
    if (length + 3 > data.length) {
      enlarge(3);
    }
    byte[] data = this.data;
    data[length++] = (byte) b;
    data[length++] = (byte) (s >>> 8);
    data[length++] = (byte) s;
    this.length = length;
    return this;
  }

  /**
   * Puts an int into this byte vector. The byte vector is automatically enlarged if necessary.
   *
   * @param i an int.
   * @return this byte vector.
   */
  public ByteVector putInt(final int i) {
    int length = this.length;
    if (length + 4 > data.length) {
      enlarge(4);
    }
    byte[] data = this.data;
    data[length++] = (byte) (i >>> 24);
    data[length++] = (byte) (i >>> 16);
    data[length++] = (byte) (i >>> 8);
    data[length++] = (byte) i;
    this.length = length;
    return this;
  }

  /**
   * Puts a long into this byte vector. The byte vector is automatically enlarged if necessary.
   *
   * @param l a long.
   * @return this byte vector.
   */
  public ByteVector putLong(final long l) {
    int length = this.length;
    if (length + 8 > data.length) {
      enlarge(8);
    }
    byte[] data = this.data;
    int i = (int) (l >>> 32);
    data[length++] = (byte) (i >>> 24);
    data[length++] = (byte) (i >>> 16);
    data[length++] = (byte) (i >>> 8);
    data[length++] = (byte) i;
    i = (int) l;
    data[length++] = (byte) (i >>> 24);
    data[length++] = (byte) (i >>> 16);
    data[length++] = (byte) (i >>> 8);
    data[length++] = (byte) i;
    this.length = length;
    return this;
  }

  /**
   * Puts an UTF8 string into this byte vector. The byte vector is automatically enlarged if
   * necessary.
   *
   * @param s a String.
   * @return this byte vector.
   */
  public ByteVector putUTF8(final String s) {
    int charLength = s.length();
    int len = length;
    if (len + 2 + charLength > data.length) {
      enlarge(2 + charLength);
    }
    byte[] data = this.data;
    // optimistic algorithm: instead of computing the byte length and then
    // serializing the string (which requires two loops), we assume the byte
    // length is equal to char length (which is the most frequent case), and
    // we start serializing the string right away. During the serialization,
    // if we find that this assumption is wrong, we continue with the
    // general method.
    data[len++] = (byte) (charLength >>> 8);
    data[len++] = (byte) charLength;
    for (int i = 0; i < charLength; ++i) {
      char c = s.charAt(i);
      if (c >= '\001' && c <= '\177') {
        data[len++] = (byte) c;
      } else {
        int byteLength = i;
        for (int j = i; j < charLength; ++j) {
          c = s.charAt(j);
          if (c >= '\001' && c <= '\177') {
            byteLength++;
          } else if (c > '\u07FF') {
            byteLength += 3;
          } else {
            byteLength += 2;
          }
        }
        data[length] = (byte) (byteLength >>> 8);
        data[length + 1] = (byte) byteLength;
        if (length + 2 + byteLength > data.length) {
          length = len;
          enlarge(2 + byteLength);
          data = this.data;
        }
        for (int j = i; j < charLength; ++j) {
          c = s.charAt(j);
          if (c >= '\001' && c <= '\177') {
            data[len++] = (byte) c;
          } else if (c > '\u07FF') {
            data[len++] = (byte) (0xE0 | c >> 12 & 0xF);
            data[len++] = (byte) (0x80 | c >> 6 & 0x3F);
            data[len++] = (byte) (0x80 | c & 0x3F);
          } else {
            data[len++] = (byte) (0xC0 | c >> 6 & 0x1F);
            data[len++] = (byte) (0x80 | c & 0x3F);
          }
        }
        break;
      }
    }
    length = len;
    return this;
  }

  /**
   * Puts an array of bytes into this byte vector. The byte vector is automatically enlarged if
   * necessary.
   *
   * @param b an array of bytes. May be <tt>null</tt> to put <tt>len</tt> null bytes into this byte
   *        vector.
   * @param off index of the fist byte of b that must be copied.
   * @param len number of bytes of b that must be copied.
   * @return this byte vector.
   */
  public ByteVector putByteArray(final byte[] b, final int off, final int len) {
    if (length + len > data.length) {
      enlarge(len);
    }
    if (b != null) {
      System.arraycopy(b, off, data, length, len);
    }
    length += len;
    return this;
  }

  /**
   * Enlarge this byte vector so that it can receive n more bytes.
   *
   * @param size number of additional bytes that this byte vector should be able to receive.
   */
  private void enlarge(final int size) {
    int length1 = 2 * data.length;
    int length2 = length + size;
    byte[] newData = new byte[length1 > length2 ? length1 : length2];
    System.arraycopy(data, 0, newData, 0, length);
    data = newData;
  }
}
